A saw apparatus includes a guide bar, a chain driver, and an endless cutting chain trained about the guide bar and the chain driver. A hydraulic chain tensioning apparatus has a hydraulic actuator configured to be driven by a hydraulic power source to act against the guide bar to maintain tension in the cutting chain. A tension release valve is provided between the hydraulic power source and the hydraulic actuator. The tension release valve has a check valve, and a manual override press-button configured to maintain the check valve in an open condition while depressed. The tension release valve has a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released.

A saw apparatus includes a guide bar, a chain driver, and an endless cutting chain trained about the guide bar and the chain driver. A hydraulic chain tensioning apparatus has a hydraulic actuator configured to be driven by a hydraulic power source to act against the guide bar to maintain tension in the cutting chain. A tension release valve is provided between the hydraulic power source and the hydraulic actuator. The tension release valve has a check valve, and a manual override press-button configured to maintain the check valve in an open condition while depressed. The tension release valve has a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released.

Tensioning devices for maintaining tension in a chain of a chain saw are disclosed. The devices may include a housing adapted to be coupled to a drive cog of a chain saw, a saw bar mount adapted to be coupled to a saw bar of a chain saw, and at least one spring adapted to bias the saw bar mount in a distal direction from the housing, thereby tensioning the spring. The tensioning device may also include a ratchet and pawl assembly that allows the saw bar mount to be moved in the distal direction and stops movement of the saw bar mount in a proximal direction. The tensioning device may also include a lock adapted to hold the saw bar mount in a proximal position against a biasing force of the spring. Methods of assembling and operating tensioning devices are also disclosed.

Tensioning devices for maintaining tension in a chain of a chain saw are disclosed. The devices may include a housing adapted to be coupled to a drive cog of a chain saw, a saw bar mount adapted to be coupled to a saw bar of a chain saw, and at least one spring adapted to bias the saw bar mount in a distal direction from the housing, thereby tensioning the spring. The tensioning device may also include a ratchet and pawl assembly that allows the saw bar mount to be moved in the distal direction and stops movement of the saw bar mount in a proximal direction. The tensioning device may also include a lock adapted to hold the saw bar mount in a proximal position against a biasing force of the spring. Methods of assembling and operating tensioning devices are also disclosed.

A chain saw has a housing, a guiding plate, a chain, a power system and a tensioning component. The tensioning component includes a knob, a driving member and a transmission assembly. When the chain is in a loose state, the knob is forced to rotate and drives the transmission assembly to rotate, and the transmission assembly drives the driving member to rotate, then the driving member drives the guiding plate to move to tension the chain. When the chain is in an extension state, the knob is forced to rotate, the driving member stays still, and a skidding inside the tensioning component is generated. The tensioning component of the chain saw of the present invention can tension the chain and fix the guiding plate by rotating the knob, the operation is simple and convenient; Meanwhile, the tensioning component avoids over-tensioning the chain by skidding inside.

A chain saw has a housing, a guiding plate, a chain, a power system and a tensioning component. The tensioning component includes a knob, a driving member and a transmission assembly. When the chain is in a loose state, the knob is forced to rotate and drives the transmission assembly to rotate, and the transmission assembly drives the driving member to rotate, then the driving member drives the guiding plate to move to tension the chain. When the chain is in an extension state, the knob is forced to rotate, the driving member stays still, and a skidding inside the tensioning component is generated. The tensioning component of the chain saw of the present invention can tension the chain and fix the guiding plate by rotating the knob, the operation is simple and convenient; Meanwhile, the tensioning component avoids over-tensioning the chain by skidding inside.

A chainsaw includes a chain tension mechanism. The chain tension mechanism includes: an adjustment dial made of resin and rotatable about an axis in a right-left direction; a rotation transmission member made of metal and rotatable about an axis in the right-left direction; a feed screw member made of metal and rotatable about an axis in a front-rear direction; and a slide member coupled to a guide bar. The slide member is screwed to the feed screw member. A first gear of the adjustment dial is meshed with a second gear of the rotation transmission member, and a first bevel gear of the rotation transmission member is meshed with a second bevel gear of the feed screw member.

A chainsaw includes a chain tension mechanism. The chain tension mechanism includes: an adjustment dial made of resin and rotatable about an axis in a right-left direction; a rotation transmission member made of metal and rotatable about an axis in the right-left direction; a feed screw member made of metal and rotatable about an axis in a front-rear direction; and a slide member coupled to a guide bar. The slide member is screwed to the feed screw member. A first gear of the adjustment dial is meshed with a second gear of the rotation transmission member, and a first bevel gear of the rotation transmission member is meshed with a second bevel gear of the feed screw member.

A chainsaw including a body including a bar stud extending therefrom; a guide bar including a bar stud slot that receives the bar stud, wherein the bar stud slot has a length, and wherein the guide bar is configured to receive a chain; a yoke having a groove defining a length extending in a direction angularly offset from the length of the bar stud slot of the guide bar, wherein the yoke is coupled to the guide bar; a ratchet gear including a one-way motion feature and a post extending into the groove of the yoke, wherein rotating the ratchet gear in a first direction moves the guide bar to tighten the chain, and wherein rotating the ratchet gear in a second direction moves the guide bar to loosen the chain; and a pawl selectively engaged with the one-way motion feature of the ratchet gear.

A chainsaw including a body including a bar stud extending therefrom; a guide bar including a bar stud slot that receives the bar stud, wherein the bar stud slot has a length, and wherein the guide bar is configured to receive a chain; a yoke having a groove defining a length extending in a direction angularly offset from the length of the bar stud slot of the guide bar, wherein the yoke is coupled to the guide bar; a ratchet gear including a one-way motion feature and a post extending into the groove of the yoke, wherein rotating the ratchet gear in a first direction moves the guide bar to tighten the chain, and wherein rotating the ratchet gear in a second direction moves the guide bar to loosen the chain; and a pawl selectively engaged with the one-way motion feature of the ratchet gear.